iMovie 10.0.1 exports to .mp4 from AVCHD .MTS files but adds popping/clicking in audio. Bug?

UPDATE: Apple Support was very helpful and worked with me to narrow this issue down to the point where it is clearly defined/repeatable and I was able to discover at least a workaround. Sharing here in case it can help anyone else.

Scenario: A certain .MTS AVCHD video clip file "Clip B" is imported into iMovie 10.0.1. and added to a movie timeline. When Clip B (about 8 minutes, 775MB) is preceded by another imported .MTS file, "Clip A", in the movie timeline, the result on playback is a popping and clicking in the audio track starting with Clip B in the movie. This is even more pronounced in the resulting rendered .out mp4 output file (using the export to file preset) but can be heard in imovie during preview playback too.

Zeroing in on the cause: No such issue occurs if Clip B is by itself in a movie, proving that Clip B itself is not corrupt with bad original audio. The issue still occurs whether Clip A precedes Clip B or even if a duplicate of Clip B precedes Clip B, thus disproving something corrupt in Clip A itself that causes a problem with later rendering Clip B. This leads to the conclusion that something in Clip B is a problem, but only for iMovie when it has to decode and render Clip B when it comes right after any other clip. By the way, these tests were done in multiple runs in fresh projects with all events/media deleted and re-imported in between, The issue persists even if using no transitions between the clips, no theme or autocontent added.

Workaround Discovery: In a new project with Clip A and Clip B added to the timeline, in that order, I split off the first 0.1 second of Clip B right at the head of it. I deleted that 0.1 second segment, and viola, no more issue at all.

Conclusion: Some type of data pattern in AVCHD .MTS clips can exist right in the very beginning of a clip (perhaps a header of some sort) such that when iMovie encounters it, but only after decoding another clip right before it, it creates an error in decoding after that point. iMovie then keeps on going and introduces corrupted audio in the resulting preview playback or rendered output movie file. So I guess I can just always trim off the first 0.1 second of every imported .MTS file and see if it never happens again, or not worry until another clip comes along that causes the same issue and then re-do the project taking that step. So far after importing about 20 different .MTS clips this only happened once and with luck it will be a rare issue. Otherwise, iMovie has been performing flawlessly with great results.